The invention relates to a method and a device for firefighting, in which a directed jet of extinguisher foam is applied so as to cover the source of the fire. Furthermore, the invention relates to a device which is suitable for implementing the method. Such devices are used in stationary or mobile firefighting units, to suffocate a fire by means of foam, for example if the use of water as a firefighting liquid is not possible.
A device suitable for firefighting with extinguisher foam is known from the British printed patent specification 1 018 431. The device described in this printed publication comprises a foam tube, a cylindrical section of which encompasses a nozzle body. The nozzle body comprises a nozzle through which firefighting liquid is applied. To let in the surrounding medium, the known device has an entry aperture at the rear. In addition, several entry apertures are arranged on the cylindrical circumference of the foam tube.
The extinguisher foam generated by means of such a device can be applied in a directional jet. This provides the advantage that the extinguisher foam exits at relatively high kinetic energy thus providing considerable reach. The fire can therefore first be fought from a great distance and subsequently from a lesser distance. At the same time the concentrated application of the jet of extinguisher foam causes the foam to impact on the location of the fire in compact form, forming a thick cover after impact, which cover suffocates the fire.
The strong concentration of the jet of extinguisher foam, which is desirable in view of the ability to cover a long range and achieve good effectiveness of the extinguisher foam, is however problematic in practical applications where fires have to be fought which have spread across large areas or which have established themselves in a substantial, compacted volume such as for example in a stack of wood or paper. Such fires can be fought by a directional jet of extinguisher foam only in that the nozzle is moved to and for during firefighting. As a result of this movement, the jet washes over the surface of the fire, covering it with extinguisher foam after a period of time. Practice shows however that due to the lack of sealing off of the fire and the increased ambient temperature, the spread of the fire to adjacent regions and objects cannot always be prevented.
It is thus the object of the invention to provide a method of the type described in the introduction and a suitable device for carrying out this method, which make it possible to extinguish fires which are spreading in area, while at the same time reducing the risk of the fire spreading.
Concerning the method, this object is met in that as a supplement to the jet of extinguisher foam, a mist of firefighting liquid is discharged which cools down the space surrounding the source of the fire.
The method according to the invention combines the firefighting method which is known per se for example from the German utility model 295 18 911.8, using firefighting mist, with the method of firefighting by means of an extinguisher foam. It has been shown that the firefighting mist and the jet of extinguisher foam ideally complement each other, in particular when fighting large-area or large-volume fires. This happens in that as a result of the directional extinguisher jet, the fire is fought directly and the top surface of the fire is gradually covered up with foam. Furthermore, the firefighting mist cools down the gas space which surrounds the fire. Since the firefighting mist covers a significantly larger space than does the jet of extinguisher foam, the application of the firefighting mist results in a lowering of the ambient temperature of the fire also in those regions where direct coverage of the fire by extinguisher foam has not yet taken place, i.e. if the fire in these particular areas is still burning. This prevents the fire from spreading, for example by spontaneous combustion of objects adjacent to the source of the fire, due to the high temperatures in the surroundings of the fire.
It is particularly advantageous if application of the firefighting mist optionally depends on the position of a control device. This makes it possible to match the composition of the firefighting agents (extinguisher foam/mist of firefighting liquid) applied to the region of the source of the fire, to the particular fire situation.
The foam tube can be used particularly advantageously in conjunction with firefighting appliances where the firefighting liquid is applied at high pressure, i.e. at pressures above 40 bar.
A further advantageous embodiment of the method according to the invention is characterized in that a mist of firefighting liquid is applied in the form of several individual jets whose respective origin is in direct proximity to the origin of the jet of extinguisher fluid. Thus it can be ensured in a simple way that most of the mist of firefighting liquid surrounds that section of the fire which is currently covered by the jet of extinguisher foam. For this reason, this embodiment is in particular advantageous in those cases where the method according to the invention is implemented by way of a mobile firefighting appliance in which the firefighter holds a mobile firefighting pistol in his/her hand. In this context it is particularly favourable if part of the individual jets of the mist of firefighting liquid is directed in the direction of the source of the fire, while another part is directed in the perpendicular way, aligned with the axis of the jet of extinguisher foam. In this way, an extended volume of space is filled with the mist of the liquid so that it is not only the space in the immediate vicinity of the fire but also the exhaust gasses rising in the surroundings, that are cooled. It is also favourable if, as a supplement or as an alternative, at least one individual jet is directed in a direction pointing away from the source of the fire so that the rear space too, of the firefighting appliance is sure to be covered by the firefighting mist.
Practical trials have shown that the method according to the invention can be used particularly effectively if the firefighting liquid from which the mist of firefighting liquid is made, is water.
A device which is particularly suitable for implementing the method according to the invention, said device comprising an extinguisher nozzle head which comprises an extinguisher foam generating device for generating a directional jet of extinguisher foam, is characterized according to the invention by the extinguisher nozzle head comprising additional extinguisher nozzles for generating jets of mist of firefighting liquid. In this, preferably at least one of the extinguisher nozzles can be aligned such that the jet of mist of firefighting liquid emanating from it, is directed in the direction of the source of the fire, while at least one further nozzle of firefighting mist is aligned such that the jet of mist of firefighting equipment emanating from it emanates in a direction aligned perpendicularly in relation to the direction of exit of the jet of extinguisher foam.
Further embodiments of the invention are stated in the dependent claims; in the following description of one embodiment they are explained in more detail by means of a drawing.